1. You don't make the proposal special.
Even if you're not the romantic type, you've got to work it a little. Asking her nonchalantly during a timeout while watching college basketball on TV isn't exactly the stuff memorable proposals are made of. You can do better than that, dude! Is there a place that holds happy memories for both of you like where you first met or said "I love you"? Give it some thought and you'll upgrade your proposal from blah to brilliant!
2. You make it too special.
You've been wowed by over-the-top viral proposals that involve flash mobs, celebrities, or dogs dressed as bridesmaids, and you feel pressure to come up with one that's a-million-page-views-worthy too. But don't make YouTube your inspiration—a simple proposal that she hears only once (no video!) is very special too, maybe more so.
3. You make it too public.
You've seen those big-screen proposals at sporting events or concerts, where some guy gets on bended knee as thousands of stadium strangers cheer him on. You decide you want to be that guy! Please don't, unless your girlfriend shares your enthusiasm for public displays of attention. More often than not, the shocked girlfriend will actually be mortified. If she's an introvert, tailor your proposal to a more intimate setting where there's no audience but the two of you.
4. You pick a bad time.
Asking her to marry you when she is sick with the flu, racing to meet a work deadline, or looking for her pet iguana that's on the loose all fall under the "bad timing" category. Wait at least until she's able to run out for a manicure.
5. You hide the ring in food or a drink.
And then she choked on it, swallowed it, or chipped her tooth. Running to the ER or dentist is very unromantic, so just leave the ring in the box until your knee is on the floor, okay?
6. You blab your secret proposal plans to a friend.
You told your best buddy who told a mutual friend who told a gal pal who happens to work with your girlfriend's cousin and now she knows. Nice job of keeping it a secret! Loose lips sink ships and ruin surprise proposals, so keep your lips shut.
7. You hand her the ring box.
That's so lame. Follow these instructions instead: Step 1) Tell her why you love her and want to spend forever together. Step 2) Get down on bended knee (left or right, your choice). Step 3) Ask "Will you marry me?" Step 4) Wait for her answer (hopefully "yes"). Step 5) Take the ring out of the box and place it on the fourth finger (the one next to the pinky) of her left hand. Step 6) Hug, cry, call parents, live happily ever after.